Multi-channel transceiver with laser array and photonic integrated circuit

ABSTRACT

A laser module can include: a laser chip having a plurality of laser diodes; a focusing lens optically coupled to each of the plurality of distinct laser diodes; and a photonic integrated circuit (PIC) having a plurality of optical inlet ports optically coupled to the plurality of laser diodes through the focusing lens. The laser module can include an optical isolator optically coupled to the focusing lens and PIC and positioned between the focusing lens and PIC. The laser chip can include a fine pitch laser array. The laser module can include a plurality of optical fibers optically coupled to an optical outlet port of the PIC. The laser module can include a hermetic package containing the laser chip and having a single focusing lens positioned for the plurality of laser diodes to emit laser beams there through.

CROSS-REFERENCE

This patent application is a Continuation of U.S. patent applicationSer. No. 14/215,520 filed Mar. 17, 2014, which claims priority to U.S.Provisional Application No. 61/791,495 filed Mar. 15, 2013, both ofwhich are incorporated herein by reference in their entirety.

BACKGROUND

Lasers have become useful in a number of applications. For example,lasers may be used in optical communications to transmit digital dataacross a fiber-optic network. The laser or laser light emitted therefrommay be modulated by a modulation signal, such as an electronic digitalsignal, to produce an optical signal transmitted on a fiber-optic cable.An optically sensitive device, such as a photodiode, is used to convertthe optical signal to an electronic digital signal transmitted throughthe fiber-optic network. Such fiber-optic networks enable moderncomputing devices to communicate at high speeds and over long distances.

Communication modules, such as electronic or optoelectronictransmitters, transceivers, or transponder modules are increasingly usedin electronic and optoelectronic communication. Communication modulesoften communicate with a host computing device via a printed circuitboard (PCB) by transmitting and/or receiving electrical data signals toand/or from the host computing device PCB. The electrical data signalscan also be transmitted by the communication module outside a hostdevice as optical and/or electrical data signals. Many communicationmodules include an optical subassembly (OSA) such as a transmitteroptical subassembly (TOSA) and/or receiver optical subassembly (ROSA) toconvert between the electrical and optical domains.

Generally, TOSA transforms an electrical signal received from the hostcomputing device to an optical signal that is transmitted onto anoptical fiber or other transmission medium. A laser diode or similaroptical transmitter included in the TOSA is driven to emit the opticalsignal representing the electrical signal received from the hostcomputing device. A ROSA transforms an optical signal received from anoptical fiber or another source to an electrical signal that is providedto the host computing device. A photodiode or similar optical receiverincluded in the ROSA transforms the optical signal to the electricalsignal.

The communication modules having the TOSA and/or ROSA can beimplemented, for example, in high power computing applications such asbetween elements in data centers. In particular, a TOSA can includevertical-cavity surface-emitting lasers (VCSELs) positioned in a firstelement. A single mode VCSEL can transmit optical signal having a singlewavelength along a single mode (SM) fiber. Also, a multimode VCSELstransmit optical signals having multiple wavelengths along a multimode(MM) fiber. The optical fibers can be connected to an ROSA in a secondnetwork element. The ROSA can include one or an array of pinphotodiodes, for example. The ROSA can receive the optical signals fromthe TOSA over the optical fibers.

However, the power consumption requirements for the TOSA and/or ROSAoptical interconnects are decreasing as the number of such opticalinterconnects increases. Thus, in data centers and in other high powercomputing applications, the optical interconnects act as powerbottlenecks.

Recently, silicon photonics have been demonstrated as an alternativetechnology, which can form the basis of some optical interconnects.Generally, silicon photonics enable the communication of optical signalsthrough a photonic circuit built on the silicon substrate. Becausesilicon substrates are already a medium of an electrical integratedcircuit (IC), the incorporation of optical components into a siliconchip with electrical elements can be obtained using silicon photonics toform a photonic integrated circuit (PIC).

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one exemplary technology area where some embodimentsdescribed herein may be practiced.

SUMMARY

In one embodiment, a laser module can include: a laser chip having aplurality of laser diodes; a focusing lens optically coupled to each ofthe plurality of distinct laser diodes; and a photonic integratedcircuit (PIC) having a plurality of optical inlet ports opticallycoupled to the plurality of laser diodes through the focusing lens. Thelaser module can include an optical isolator optically coupled to thefocusing lens and PIC and positioned between the focusing lens and PIC.The laser chip can include a fine pitch laser array, wherein the finepitch laser array can have a pitch from about 10 microns to about 50microns. In one aspect, the plurality of laser diodes can emit laserbeams that have the same wavelength. In one aspect, two or more of theplurality of laser diodes emit laser beams that have differentwavelengths. The laser module can include a plurality of optical fibersoptically coupled to an optical outlet port of the PIC. In one aspect,the PIC can have more optical output channels than the laser chip haslaser diodes, wherein the number of optical output channels can be atleast twice the number of laser diodes on the laser chip. The lasermodule can include a hermetic package containing the laser chip andhaving a single focusing lens positioned for the plurality of laserdiodes to emit laser beams there through.

In one embodiment, the PIC can include: an integrated waveguide for eachoptical inlet port; an optical splitter optically coupled to eachintegrated waveguide that splits into two or more optical channelsdownstream from the optical splitter; and an integrated modulator foreach optical channel. The plurality of optical inlet ports of the PICcan have a pitch of about 3× or 4× the pitch of the fine pitch laserarray. The PIC can include a receiver photodiode.

In one embodiment, the laser module can include a wavelength-divisionmultiplexing (WDM) device optically coupled to an optical outlet port ofthe PIC.

In one embodiment, a transmitter can have a laser module including: alaser chip having a plurality of laser diodes in a fine pitch laserarray; a focusing lens optically coupled to each of the plurality ofdistinct laser diodes; an optical isolator optically coupled to thefocusing lens; and a photonic integrated circuit (PIC) having aplurality of optical inlet ports optically coupled to the plurality oflaser diodes through the focusing lens and optical isolator, wherein thePIC has at least twice more optical output channels than the laser chiphas laser diodes. The transmitter can include a hermetic packagecontaining the laser chip and having a single focusing lens positionedfor the plurality of laser diodes to emit laser beams there through. ThePIC of the transmitter can include: the plurality of optical inlet portshaving a pitch of about 3× or 4× the pitch of the fine pitch laserarray; an integrated waveguide for each optical inlet port; an opticalsplitter optically coupled to each integrated waveguide that splits intotwo or more optical channels downstream from the optical splitter; andan integrated modulator for each optical channel.

In one embodiment, a transceiver can include a transmitter laser modulehaving: a laser chip having a plurality of laser diodes in a fine pitchlaser array; a focusing lens optically coupled to each of the pluralityof distinct laser diodes; an optical isolator optically coupled to thefocusing lens; and a photonic integrated circuit (PIC) having aplurality of optical inlet ports optically coupled to the plurality oflaser diodes through the focusing lens and optical isolator, wherein thePIC has at least twice more optical output channels than the laser chiphas laser diodes. The transceiver also includes a receiver photodiode.The transceiver can include a hermetic package containing the laser chipand having a single focusing lens positioned for the plurality of laserdiodes to emit laser beams therethrough. The PIC can include: aplurality of optical inlet ports having a pitch of about 3× or 4× thepitch of the fine pitch laser array; an integrated waveguide for eachoptical inlet port; an optical splitter optically coupled to eachintegrated waveguide that splits into two or more optical channelsdownstream from the optical splitter; and an integrated modulator foreach optical channel. In one aspect, the PIC can include the receiverphotodiode. In one aspect, a receiver module separate from thetransmitter laser module can include the receiver photodiode.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and following information as well as other features ofthis disclosure will become more fully apparent from the followingdescription and appended claims, taken in conjunction with theaccompanying drawings. Understanding that these drawings depict onlyseveral embodiments in accordance with the disclosure and are,therefore, not to be considered limiting of its scope, the disclosurewill be described with additional specificity and detail through use ofthe accompanying drawings.

FIG. 1 illustrates an embodiment of a transmitter.

FIG. 1A illustrates an embodiment of a transceiver having separate TOSAand ROSA.

FIG. 1B illustrates an embodiment of a transceiver with a photonicintegrated circuit (PIC) having a receiver photodiode.

FIG. 2 illustrates an embodiment of a laser module.

FIG. 2A illustrates an embodiment of a laser array and hermetic packagefor a laser module.

FIG. 2B illustrates an embodiment of a PIC.

FIG. 2C illustrates another embodiment of a PIC.

FIG. 2D illustrates yet another embodiment of a PIC.

FIG. 2E illustrates an embodiment of a portion of a PIC.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

Generally, the present invention includes a laser module having a laserarray optically coupled with a photonic integrated circuit (PIC) havinga plurality of output optical fibers. The laser array can include aplurality of lasers that are separate from each other or a plurality oflaser emitters in a single laser package or single laser substrate. Thelaser array can be a pitched laser array. The laser array may be a finepitched laser array. The lasers can include continuous wave lasers, suchas continuous wave (CW) distributed feedback (DFB) laser or distributedBragg reflector (DBR) laser. As such, the laser can include a finepitched CW DFB laser array with a PIC. The output optical fibers fromthe PIC can be one or more unique optical fibers or a fiber ribbonhaving a plurality of optical fibers therein. The laser module caninclude one or more output optical fibers for each of the lasers in thelaser array. While the CW DFB laser array is described herein, theprinciples can be applied to other laser arrays as known or developed inthe art.

The laser module having the fine pitched laser array with a PIC can beconfigured for single mode (SM) and/or multi-mode (MM) operation. Assuch, the laser module having the fine pitched laser array with a PICcan be configured for high density optical communication platforms. Inone aspect, the laser array can include a plurality of high power CWlaser as the optical sources. However, the laser array can include DFBlasers as the optical source in order to provide high speed optical datatransmission. The DFB lasers can be configured as low power opticalsources. The DFB lasers of the laser array can be configured asdescribed herein or generally known in the art.

The laser module having the fine pitched laser array with a PIC can beconfigured for high density and high speed parallel SM-MM optical datatransmission. As such, the laser module can include a PIC with aplurality of optical inlets and a plurality of optical outlets. The PICcan receive two or more optical light beams from the laser array andtransmit optical light through a plurality of output optical fibers. Thelaser array thereby provides the optical source for the PIC for parallelSM and MM fiber optical communications.

In one embodiment, the laser module can be included in a transmittermodule or a transceiver module. The transceiver can have the finepitched laser array with PIC as a transmitter and any type of receivercompatible therewith. For example, the receiver can be any type ofphotodiode receiver, which may be packaged with the transmitter orseparately therefrom in the transceiver module. Also, the PIC can beconfigured as a receiver of a transceiver.

Embodiments of the invention described herein may be implemented inoptoelectronic devices. As used herein, the term “optoelectronic device”includes a device having both optical and electrical components.Examples of optoelectronic devices include, but are not limited totransponders, transceivers, transmitters, and/or receivers. While someembodiments described herein will be discussed in the context of atransceiver module, those of skill in the art will recognize that theprinciples of the present invention may be implemented in virtually anydevice having some or all of the functionality described herein. Theprinciples of the invention can be implemented in optoelectronic devicesof any form factor such as XFP, SFP, SFP+, SFF, XENPAK, and XPAK, orothers known or developed without restriction. Alternatively oradditionally, the optoelectronic device can be suitable for opticalsignal transmission and reception at a variety of per-second data rates,including but not limited to 1 gigabit per second (Gbit), 2 Gbit, 4Gbit, 8 Gbit, 10 Gbit, 14 Gbit, 20 Gbit or other bandwidth fiber opticlinks. Furthermore, optoelectronic devices of other types andconfigurations, or having components that differ in some respects fromthose shown and described herein, can also benefit from the principlesdisclosed herein.

FIG. 1 illustrates an embodiment of an operating environment of atransmitter 100 including a laser module 110 having a laser array 112optically coupled with a PIC 114. As shown, the transmitter 100 includesthe laser module 110 having the laser array 112 optically coupled tooptical components 116 that are optically coupled to a PIC 114.

The laser module 110, through the optical components 116 and PIC 114, isoptically coupled to an optical outlet port 102 in the transmitter 100that is optically coupled to an outlet optical fiber ribbon 104 from thetransmitter 100. This embodiment of the invention as well as all otherembodiments of the invention can be combined or modified with otherembodiments or include other principles or elements described herein.

FIG. 1A shows a transceiver 100 a that includes a TOSA 110 and ROSA 120.

The TOSA has the laser array 112 optically coupled to the opticalcomponents 116 that are optically coupled to the PIC 114. The TOSA 110,through the optical components 116 and PIC 114, is optically coupled toan optical outlet port 102 in the transceiver 100 a that is opticallycoupled to an outlet optical fiber ribbon 104 from the transceiver 100a. The transceiver 100 a also includes the ROSA 120 optically coupled anoptical inlet port 106 that is optically coupled to an inlet fiber 108,such as a single fiber or fiber ribbon.

FIG. 1B also shows a transceiver 100 b that includes a laser module 110a having the laser array 112 optically coupled to optical components 116that are optically coupled to a PIC 114 a. The laser module 110, throughthe optical components 116 and PIC 114 a, is optically coupled to anoptical outlet port 102 in the transceiver 100 b that is opticallycoupled to an outlet optical fiber ribbon 104 from the transceiver 100b. The transceiver 100 b also includes a receiver 120 a that is embeddedin or integrated with the PIC 114 a of the laser module 110 a. Thereceiver 120 a is optically coupled an optical inlet port 106 of thetransceiver 110 b that is optically coupled to an inlet fiber 108.

FIG. 2 illustrates a laser module 210 having the laser array 212optically coupled to optical components 216 that are optically coupledto the PIC 214. The laser module 210, through the optical components 216and PIC 214, is optically coupled to an optical outlet port 202 that isoptically coupled to an outlet optical fiber ribbon 204. The lasermodule 210 includes a hermetic housing 230 that is hermetically sealedthat contains the laser array 212. The hermetic housing 230 can beevacuated or gas (e.g., air, nitrogen, halogen, etc.) filed. The laserarray 212 includes a single laser chip 232 that has a first laser diode234 separate from a second laser diode 236 by a defined separationpitch. The first laser diode 234 emits a first laser beam 234 a of afirst wavelength and the second laser diode 236 emits a second laserbeam 236 a of a second wavelength, where the first and secondwavelengths can be the same, substantially the same (e.g., +/−10%, 5%,2%, 1%), or different (e.g., 1310 nm and 1550 nm). The first laser beam234 a and second laser beam 236 a pass through a focusing lens 238before passing through an optical isolator 240. The focusing lens 238focuses the first laser beam 234 a to a first optical inlet port 242 onthe PIC 214 and focuses the second laser beam 236 a to a second opticalinlet port 244 on the PIC 214. It is noted that as illustrated, thefirst laser beam 234 a and second laser beam 236 a; however, the may beseparate and focused into the PIC 214 with or without crossing. Whilethe focusing lens 238 is only shown with the output surface being curvedor rounded, the input surface can also be curved or rounded asillustrated and described herein. The optical isolator 240 can be a freespace isolator such as having a faraday rotor bound on both ends bypolarizers. The hermetic housing 230, focusing lens 238, and isolator240 can be configured as standard in the art, and can include any typethereof.

FIG. 2A illustrates an embodiment of a portion of the laser module ofFIG. 2, which shows the laser array 212 in the hermetic housing 230optically coupled through the focusing lens 238 and isolator 240 withthe PIC 214. The laser array 212 is shown to have a laser chip 232having a plurality of laser diodes 234, 235, 236, 237; however, anynumber of laser diodes can be included on the laser chip 232 as shown bythe bracket and N is an integer defining the number of laser diodes onthe laser chip 232. Alternatively, the bracket and N can define thenumber of individual laser chips 232 in the hermetic housing 230, whereN is an integer. The plurality of laser diodes 234, 235, 236, 237 eachemit laser beams 234 a, 235 a, 236 a, 237 a that are focused by thefocusing lens 238 onto discrete locations on the PIC 214. The focusedlaser beams 234 a, 235 a, 236 a, 236 a pass through the isolator 240.

FIG. 2B illustrates an embodiment of the PIC 214 illustrated in FIG. 2.The PIC 214 is shown to include the first optical inlet port 242receiving the first focused laser beam 234 a and second optical inletport 244 receiving the second focused laser beam 236 a. The firstoptical inlet port 242 is optically coupled to a first waveguide 252 orwaveguide circuit thereof and the second optical port 244 is opticallycoupled to a second waveguide 272 of waveguide circuit thereof. Thefirst waveguide 252 is optically coupled to a first optical splitter 254that splits the first laser beam 234 into two first channels 256 a, 256b. The second waveguide 272 is optically coupled to a second opticalsplitter 274 that splits the second laser beam 236 a into two secondchannels 276 a, 276 b. Each of the two first channels 256 a, 256 b aremodulated by first modulators 258 a, 258 b so as to provide data ontothe laser beams therein. Each of the two second channels 276 a, 276 bare modulated by second modulators 278 a, 278 b so as to provide dataonto the laser beams therein. Each of the two first modulators 258 a,258 b output modulated laser beams in output channels 260 a, 260 b,which are in turn optically coupled to an optical port 290 that isoperably coupled to a fiber ribbon 292. Each of the two secondmodulators 278 a, 278 b output modulated laser beams in output channels280 a, 280 b, which are in turn optically coupled to the optical port290. The fiber ribbon 292 is shown to include an optical fiber 294 foreach of the output channels 260 a, 260 b, 280 a, 280 b.

FIG. 2B also shows that the PIC 214 can include an electronic component298, such as any electron component described herein or known in the artto be included in a PIC. FIG. 2B also shows that the PIC can include anoptoelectronic component 299, such as any optoelectronic componentdescribed herein or known in the art to be included in a PIC. FIG. 2Calso shows that the PIC can include an optical component 297, such asany optical component described herein or known in the art to beincluded in a PIC. The locations of the optical component 297,electronic component 298, and/or optoelectronic component 299 can be asneed or desired or standard or known in a PIC. Also, any number of thesame type or different types of the optical component 297, electroniccomponent 298, and/or optoelectronic component 299 can be included inthe PIC.

FIG. 2C is similar to FIG. 2B; however, the beam splitters 254, 274 eachsplit the laser beam into 4 different beams, which are modulated androuted to the optical fiber ribbon 292. The first waveguide 252 isoptically coupled to a first optical splitter 254 that splits the firstlaser beam 234 into four first channels 256 a, 256 b, 256 c, 256 d. Thesecond waveguide 272 is optically coupled to a second optical splitter274 that splits the second laser beam 236 a into four second channels276 a, 276 b, 276 c, 276 d. Each of the four first channels 256 a, 256b, 256 c, 256 d are modulated by first modulators 258 a, 258 b, 258 c,258 d so as to provide data onto the laser beams therein. Each of thefour second channels 276 a, 276 b, 276 c, 276 d are modulated by secondmodulators 278 a, 278 b, 278 c, 278 d so as to provide data onto thelaser beams therein. Each of the four first modulators 258 a, 258 b, 258c, 258 d output modulated laser beams in output channels 260 a, 260 b,260 c, 260 d which are in turn optically coupled to the optical port 290that is operably coupled to the fiber ribbon 292. Each of the foursecond modulators 278 a, 278 b, 278 c, 279 d output modulated laserbeams in output channels 280 a, 280 b, 280 c, 280 d which are in turnoptically coupled to the optical port 290. The fiber ribbon 292 is shownto include an optical fiber 294 for each of the output channels 260 a,260 b, 260 c, 260 d, 280 a, 280 b, 280 c, 280 d.

FIG. 2D is substantially similar to FIG. 2B; however, the PIC 214includes or is optically coupled to a wavelength-division multiplexing(WDM) device 295. This can allow for multiple wavelengths to be coupledinto the same optical fibers 294 of the fiber ribbon 292.

FIG. 2E shows that the PIC 214 can be configured to include any numberof optical inlet ports 244 and corresponding waveguides, opticalsplitters, and channels, or the like, which is shown by the bracket an Nis an integer.

In one embodiment, the laser module can include a fine pitched DFB laserarray as the optical source for 4-channel or higher parallelapplications. In one example, the fine pitched DFB laser array can beused in place of a single high power CW laser for 4-channel parallelapplications. The 4 channels can be from two laser diodes on a laserchip emitting 2 laser beams that are each split into two more laserbeams by the PIC to form 4 separate laser beams. This configuration canbe multiplied by 2, 4, 6, 8, or higher as chip technology and hermeticpackaging techniques approve in order to increase the number of channelsavailable.

In one embodiment, one or more of the DFB lasers in the laser array caninclude about 10 mW optical power. However, higher optical power foreach DFB laser can be used. The DFB laser array can be configured to besufficient for long range (LR) data transmission, where LR datacommunication can be at least or about 10 km. The DFB laser array can beconfigured for 10G LR data transmission. In one example, the DFB laserarray can be configured for 4-channel 10G LR (e.g., 4×10G-LR) datacommunication applications. Such configurations of DFB lasers withsufficient power utilize the PIC for the data communication applicationsthat are described. For example, a common DFB laser at 1310 nm can haveabout 10 mW optical power, and application with the PIC can obtain the10G LR data transmission, such as in the 4×10G-LR data communicationapplications.

In one embodiment, the laser array can include a plurality of 20 mWsingle CW lasers, which can be configured for 4×10G-LR (10 km)applications. A 20 mW single CW laser is considered to be a higherpowered laser compared to the DFB lasers that can be used, such as 10 mWDFB lasers. However, DFB laser arrays can be preferred over higherpowered non-DFB CW lasers.

In one embodiment, the laser module can include one or more fine pitched2×1 laser arrays, which includes 2 laser diodes on 1 laser chip. Thiscan allow proven DFB chip technology to be implemented and combined withthe PIC via the focusing lens, and optionally the isolator, for thelaser module of the present invention. However, the laser module caninclude other types of laser arrays and other laser array arrangements.In one aspect, the laser array can be a linear laser array. In anotheraspect, the laser array can include a grid laser array having laser rowsand laser columns, where the figures can show such an array by showingthe lasers on an edge of the array, which can be top, bottom, or sidesof the array. For example, the laser module can include laser arrayswith high numbers of lasers in order to obtain higher channel countapplications. Some examples of laser arrays an include 2, 4, 6, 8, 10,12, 14, 16, 18, or 20 or higher lasers as laser chip manufacturingtechnologies advance. The lasers in the array may be individual laserson separate substrates or a single substrate having multiple lasers, orcombinations thereof. Some examples of laser arrays can include DFBlaser arrays configured as 10×10G or 10×25G lasers, where the 10indicates the number of channels output from the PIC.

In one embodiment, the laser chip can be a fine pitch laser chip, wherethe pitch is considered the distance or mechanical dimension betweenadjacent laser diodes on the same laser chip. Fine pitch laser chips areconsidered to have less than or about 50 μm between adjacent laserdiodes. In one aspect, the fine pitch laser chip can have between 10 μmpitch and 50 μm pitch, between 20 μm pitch and 40 μm pitch, between 25μm pitch and 35 μm pitch, or about 30 μm pitch. Data has shown that 10μm pitch laser chips can be prepared. Some fine pitch laser chipexamples can be 12 μm pitch or 15 μm pitch. The unique laser diodes canfit in a single hermetic package that uses only single opticalcomponents, which focus the unique lasers onto unique laser spots ontothe PIC optical inlet ports. Additionally, the PIC can have a pitch,which is the distance between the optical inlet ports thereof. The PICpitch can be 3-4 times the laser array pitch. If the optical inlet portshave a 100 micron pitch on the PIC, then there is about a 25 micronpitch on the laser array. Similarly, the PIC pitch can be calculatedbased on the laser array pitch.

In one embodiment, the plurality of lasers in the laser array of thelaser module of the present invention can be included in the samehermetic package. However, the lasers of the laser array may optionallybe in separate hermetic packages. The application of the lasers in thelaser array in the same hermetic package can reduce costs because thelasers can share the same optical components, such as same lens,collimating lens, focusing lens, isolator, wave plate, mirror, tiltmirror, MEMS tilt mirror, waveguides, diffraction gratings, or otheroptical components or optical features employed in laser modules.

In one embodiment, the lasers of the laser array can share one or moreof the same optical components, such as same lens, collimating lens,focusing lens, isolator, wave plate, mirror, tilt mirror, MEMS tiltmirror, waveguides, diffraction gratings, or other optical components oroptical features employed in laser modules. Such sharing can be employedwhen the lasers are in the same hermetic package or in differenthermetic packages. However, whether in the same hermetic package ordifferent hermetic packages, each of the lasers of the laser array mayoptionally include its own optical components, such as same lens,collimating lens, focusing lens, isolator, wave plate, mirror, tiltmirror, MEMS tilt mirror, waveguides, diffraction gratings, or otheroptical components or optical features employed in laser modules.

In one embodiment, the hermetic package has a single lens, which isconfigured as a focusing lens. The focusing lens can have a roundedlight receiving side and a rounded light emitting side. That is, bothsides of the focusing lens can be rounded or curved. However, only oneside of the focusing lens may be rounded or curved in one aspect. Thehermetic package can include a lens frame for the lens. The singlefocusing lens can form specific focused spots from each laser diode ofthe laser array on the PIC. The focused spots can be at optical inletports of the PIC.

In one embodiment, the lasers of the laser array can each include thesame or substantially the same wavelengths of emitted laser light. Inone aspect, each laser diode on the laser chip can be substantiallyexactly the same. The laser diodes on the laser chip that are the sameor similar can be DBR or DFB lasers.

Optionally, different optical components can be used to distinguishbetween the different lasers of the laser array. For example, a waveplate can be used to polarize laser light of one laser to distinguishsuch polarized light from other lasers of the laser arrays. Variouscombinations of optical components can be used when the laser array hasa plurality of lasers with the same wavelength. For example, some laserscan include no optical element, some can include ½ wave plate, some caninclude ¼ wave plates, or combinations thereof.

In one embodiment, two or more lasers of the laser array can havedifferent wavelengths that are distinguishable from each other. In oneexample, each laser can have different wavelengths from the other lasersin the laser array. The configuration of the laser can be modulated withgrating to change the wavelength. Each laser diode can have a uniquegrating kappa or corrugation to determine the wavelength.

In one embodiment, the laser module can include a wavelength-divisionmultiplexing (WDM) device in order to reduce the number of fibers out ofthe laser module. The WDM can be between the PIC and the output opticalfibers. The WDM can be after modulation. As such, multiple wavelengthscan be passed through the output optical fibers. The WDM can be used asis common in laser modules.

In one embodiment, at least one of the lasers in the laser array canemit laser light at about 1310 nm. However, all of the lasers in thelaser array can emit laser light at about 1310 nm or there about, suchas a range of wavelengths near 1310 nm. In one aspect, the laser lightcan vary from 1310 nm, such as from 1260 to 1370 nm. For example, thelaser light can vary from 1310 nm+/1 10 nm, 20 nm, 30 nm, 40 nm, 50 nm,or 60 nm.

In one embodiment, at least one of the lasers in the laser array canemit laser light at about 1550 nm. However, all of the lasers in thelaser array can emit laser light at about 1550 nm or there about, suchas a range of wavelengths near 1550 nm. In one aspect, the laser lightcan vary from 1550 nm, such as from 1490 to 1610 nm. For example, thelaser light can vary from 1310 nm+/1 10 nm, 20 nm, 30 nm, 40 nm, 50 nm,or 60 nm.

In one embodiment, the laser chip can be an InP laser chip. In oneaspect, the laser can be an InGaAsP/InP laser chip.

In one embodiment, the laser can be configured as a VCSEL. In oneaspect, the laser chip can be an InP silicon chip.

In one embodiment, the PIC can be a silicon photonic integrated circuit(SiPIC). This can use silicon technology to have multiple opticalelements, such as one or more splitter and modulator as desired for anapplication. In one aspect, the PIC can include an integrated photoreceiver (e.g., photodiode) for a transceiver application. In oneaspect, the PIC can include electronic circuits to operate theelectronic and/or optoelectronic components of the PIC, which caninclude the PIC having a laser driver, modulator driver, transimpedenceamplifier (TIA), or the like found in a PIC, which can be a siliconcircuit.

The PIC can include an optical inlet optically coupled to each of theindividual laser diodes of the hermetic package. The PIC circuitry caninclude small waveguides that are coupled to each of the optical inletoptics, which waveguides can include splitters that split the laserbeams into different channels, where the PIC can include a modulator foreach channel.

The laser module can include optical components to couple each laserbeam from each laser diode to different optical inlet ports on the PIC.This can include the laser module having a laser array in a hermeticpackage that has a single lens and an optical isolator between the lensand the PIC. The lens can be a focusing lens that focuses all of thelaser beams into unique optical inlet ports of the PIC. The PIC caninclude a 1-to-2 beam splitter for each unique laser beam, or it caninclude a 1-to-4 beam splitter for each laser beam. Also, higher inletlaser beam splitting can occur, such as 1-to-N beam splitter, where N isan integer. In the 1-to-4 beam splitter, each subsequent channel willonly receive ¼ of the light from the laser beam (minus some couplingloss or other loss). This concept can be multiplied by the number ofunique laser diodes on the laser chip, such as described herein.

In one embodiment, the PIC can include a modulator for each of thechannels formed therein. That is, each of the channels that are outputcan have a unique modulator to modulate data on the laser light passingthrough the unique channel waveguide in the PIC.

In one embodiment, the PIC can include an integrated modulator driver,such as a CMOS driver. In one aspect the PIC can include a modulatordriver that is separate but operably coupled to the modulator of thePIC.

In one embodiment, the laser module can be configured for variousarrangements and distances between the laser chip, the focusing lens,and the PIC. In one example, the laser module can be configured for 3×or 4× magnification to bring a DFB having 0.3 NA to about 0.1 NA(numeric aperture) of the PIC, which can be done with about 150 umspacing between the optical inlet ports on the PIC. This can be donesubstantially as focusing optical components as the focusing lens canfocus each unique laser beam onto a unique optical inlet port of thePIC. The lens position can be changed in position between the laser andPIC to determine magnification. To get maximum coupling ratio to getmagnification of the beam, the beam profile can define the dimensions.The laser can include a 0.3 NA to 0.4 NA, and then on the PIC side toget good coupling there can be 0.1 NA, which results from 3× to 4×magnification. The distance to the PIC from the lens divided by thedistance from the lens to laser. The NA is relative to the cone of laserlight emitted from the laser diode. The distances can be adjusted asneeded or desired.

The laser light that is focused by the focusing lens can pass through anoptical isolator. The optical isolator can be any standard or free spaceoptical isolator. In one example, the optical isolator can include twomagnets on opposite sides with a material therebetween where the lightpasses through. The middle portion that the light passes through caninclude a polarizer on each end with a faraday rotor in the middle. Suchisolators are well known in the art. However, other free space isolatorscan be used. This results in free space air gaps between the lens andisolator and free space air gaps between the isolator and PIC.

In one embodiment, the PIC can be configured with two or more opticalinlet ports that receive laser light from two different laser diodes inthe hermetic package. The PIC includes an optical waveguide for eachoptical inlet port. Each waveguide can be coupled to a beam splitter,such as a waveguide beam splitter (e.g., 2 or 4 channels from eachbeam). The splitter has two or four downstream waveguides, with onedownstream waveguide per channel, which channel waveguides are referredto herein as channels. Each channel can include a photonic modulator(e.g., integrated silicon photonic modulator), that modulates data ontoeach laser beam in the channels. The modulator can be inferiometerbased, which can be controlled by electronic signal. Each channel can becoupled to an independent fiber, which can be single fibers or fiberribbon.

Additionally, the PIC can also include: low loss interconnectwaveguides, power splitters, optical amplifiers, TIA amplifier, opticalmodulators, filters, and other elements of common PIC devices. Also, thePIC may also include additional lasers diodes. In one embodiment, thePIC can include one or more optical detectors, such as photodiodes(e.g., germanium photodiode grown in the silicon-based pic), which canbe useful when the laser module is a transceiver. As such, thephotodiodes in the PIC can be used for the receiver portion of thetransceiver and the laser chip and PIC can be used for the transceiverportion.

In one embodiment, the PIC can be configured to include one or morearrayed waveguide gratings (AWG). The AWG in the PIC can be configuredas an optical multiplexer or an optical de-multiplexer. Accordingly, thelaser module with the AWG can be configured as a wavelength divisionmultiplexed (WDM) fiber-optic communication system. In one aspect, thelaser module can include a WDM device between the PIC outlet ports andthe transmission fiber optic cables.

In one embodiment, the laser module can be configured as an externallymodulated laser (EML) with a modulator separate from the laser chip. Themodulator can be combined with the PIC in order to modulate data ontothe different channels of the PIC. The PIC can include a uniquemodulator for each channel.

One skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the essence of the disclosedembodiments. It should be understood that elements of one embodiment canbe applied to other embodiments provided herein.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to be limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, agroup having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells,and so forth.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

All references recited herein are incorporated herein by specificreference in their entirety, which can be applied to the presentinvention, including: Photonic Integration Trends, T. L. Koch, GENIOptical Workshop, Arlington, Va., Sep. 25, 2007; CMOS Photonics Today &Tomorrow, Dave D'Andrea, Microphotonics Center Spring Meeting, May 2009;Silicon Photonics: Challenges and Future, W. S. Ring, 2007; U.S. Pat.No. 7,474,813; U.S. Pat. No. 7,536,067; U.S. Pat. No. 8,280,255; U.S.2010/0220763; U.S. 2010/0284647; U.S. 2011/0222571; U.S. 2011/0249936;and U.S. 2012/0189306.

The invention claimed is:
 1. A photonic integrated circuit (PIC)comprising: a plurality of optical inlet ports integrated on a surfaceof the PIC where each individual optical inlet port is configured tooptically couple to a corresponding laser diode via a focusing lens; aplurality of waveguides each coupled to one of the plurality of opticalinlet ports; a plurality of optical splitters each coupled to one of theplurality of waveguides and each optical splitter splits into two ormore optical channels and where each optical channel is integrated inthe PIC; a plurality of modulators each coupled to one of the opticalchannels; and a plurality of output channels each coupled with one ofthe modulators.
 2. The PIC of claim 1, wherein the plurality of opticalinlet ports have a pitch of about 30 microns to about 150 microns. 3.The PIC of claim 1, wherein the plurality of optical inlet ports have apitch of about 40 microns to about 200 microns.
 4. The PIC of claim 1,comprising an optical outlet port, wherein the optical outlet port iscoupled with the plurality of output channels such that each individualoutput channel is capable of being optically coupled with one of aplurality of optical fibers.
 5. The PIC of claim 1, wherein the PIC hasmore optical output channels than optical inlet ports.
 6. The PIC ofclaim 5, wherein the number of optical output channels is at least twicethe number of optical inlet ports.
 7. The PIC of claim 4, furthercomprising a wavelength division multiplexing device optically coupledto the optical outlet port.
 8. The PIC of claim 1, further comprising anintegrated waveguide for each optical inlet port.
 9. The PIC of claim 1,further comprising an optical splitter optically coupled to eachintegrated waveguide that splits into two or more optical channelsdownstream from the optical splitter.
 10. The PIC of claim 1, furthercomprising an integrated modulator for each optical channel.
 11. The PICof claim 1, further comprising a substrate defining the PIC, thesubstrate being silicon.
 12. The PIC of claim 1, further comprising atleast one electronic component included in the PIC.
 13. The PIC of claim12, wherein the at least one electronic component is selected from laserdriver, modulator driver, transimpedence amplifier, or combinationsthereof.
 14. The PIC of claim 12, further comprising an electroniccircuit coupled to the at least one electronic component.
 15. The PIC ofclaim 1, further comprising at least one optoelectronic componentincluded in the PIC.
 16. The PIC of claim 1, wherein the at least oneoptoelectronic component includes at least one receiver photodiode. 17.The PIC of claim 5, wherein the number of optical output channels is atleast four times the number of optical inlet ports.
 18. The PIC of claim1, comprising a modulator for each optical channel.
 19. The PIC of claim15, wherein the at least one optoelectronic component includes at leastone laser diode.
 20. The PIC of claim 1, further comprising on or morearrayed waveguide gratings.